When drilling for oil and the like, it is necessary to drill deep into the ground. Accordingly, the practice is to make up a string of drill pipe from a plurality of pipe sections, with the sections being connected together at the surfaces of the well through the means of threaded joints.
A two-step procedure is generally employed when making up a string of drill pipe. The first step is the initial spinning of the above-ground section of pipe relative to the section extending into the ground until the mating threads "bottom out". The second step involves the use of pipe tongs to generate the substantial tightening torque necessary to maintain the integrity of the string during the drilling operation.
The most commonly employed technique of spinning the above-ground drill pipe through the initial five or so turns involves the use of chains. A chain is manually whipped around the drill pipe, and is then retracted, with the friction developed during the retraction of the chain spinning the upper pipe relative to its mating in-ground pipe. It has long been known that the use of heavy chains to perform the initial pipe spinning operation is quite dangerous. Indeed, many serious injuries from back-lashing chains have been inflicted.
Attempts have previously been made to eliminate some of the dangers involved in the initial spinning of drill pipe by mechanizing the spinning operation. See, for example, U.S. Pat. Nos. 1,505,007, 1,615,695, 2,615,681, 2,746,329 and 2,784,626. Of these, U.S. Pat. No. 2,615,681 issued to True on Oct. 28, 1952 is deemed to be the most advanced.
The True patent discloses a mechanized pipe spinning device mounted above tonging means, and utilizes a continuous belt, chain or other metallic member to automatically spin the drill pipe. The True device purports to accomplish the goal of eliminating human intervention and the use of dangerous chains for initial makeup operations, yet the True device is quite cumbersome, costly and prone to failure.
It is toward the improvement of the above-noted prior art techniques and devices that the present invention is directed.